Among flat display techniques, organic light emitting diode (OLED) displays possess many outstanding properties, including being light weight and having small thickness, self-illumination, short response times, wide viewing angles, wide color gamut, high brightness, and low power consumption, and thus, following liquid crystal displays, have gradually become a third generation of display techniques. Compared to liquid crystal displays (LCDs), OLED displays are more energy conscious and thinner in thickness, and have wider viewing angles. Currently, users are more unsatisfied with resolution of displays, but it is still challenging to manufacture OLED displays having high quality and high resolution.
An OLED display panel is one essential part of OLED displays. Conventionally, an OLED display panel includes a thin film transistor layer, an anode electrode layer formed on the thin film transistor layer, a pixel defining layer, a first common layer, a light-emitting layer, a second common layer, and a cathode layer. OLED display panels functionally work by transporting holes from the first common layer to the light-emitting layer and transporting electrons from the second common layer to the light-emitting layer under electric field generated between anode electrode and cathode electrode, and combining holes with electrons in the light-emitting layer, so as to achieve illumination.
Since passive displays having small area are more mature than before, active displays having large area nowadays have become the main stream where organic light-emitting development focuses. Thin film transistor (TFT) driving technique is required to achieve large area display. However, conventional bottom-emitting OLED (BOLED) devices use indium tin oxide (ITO) anode formed on transparent substrate as a light emission surface. Owing to use of a non-transparent silicon substrate, or use of a substrate composed of amorphous silicon with low mobility and organic TFT, it is prone to lead to a low aperture ratio. Therefore, to realize organic light-emitting active display screen having a large area and high brightness, top-emitting OLED devices are developed which solves the aperture ratio issue by separating the light emission surface from the substrate (TFT).
Conventionally, top-emitting OLED devices are manufactured to include a structure having a total reflection anode electrode and a semi-transparent cathode electrode to realize top-emission of OLED devices. The structure is optimized in order to effectively adjust microcavity effect of TOLED, so as to improve color of light emitted by OLED devices and enhance coupling efficiency of light emitted by devices.